1. Field of the Invention
The present invention relates to a spindle motor and a disk drive apparatus.
2. Description of the Related Art
Conventionally, a disk drive apparatus such as a hard disk drive apparatus or the like is equipped with a spindle motor for rotating a disk. The disk drive apparatus includes a disk, a housing, a stator, a FPC (Flexible Printed Circuit), and so forth. The housing includes a cover member, a base member, and so forth.
In recent years, the disk drive apparatus is required to become smaller in height and size. Particularly, in order to reduce the height of a 2.5-type disk drive apparatus having a thickness of 7 mm or less, which is used in small-size disk drive apparatuses, it is necessary to reduce the thickness of a housing or a motor arranged within the housing. In general, the motor includes a hub, a coil, a stator core, a wiring substrate, a base member, etc. When assembling the motor, these components are arranged to axially overlap with one another. For the sake of reducing the thickness of the motor, these components need to be made thin. However, if an attempt is made to reduce the overall height of the motor by reducing the turn number of the coils or the lamination thickness of the stator core, the magnetic fluxes generated in the stator during the operation of the motor will be reduced. In other words, the torque constant will be reduced. It is therefore impossible to obtain the torque required in rotating the disk attached to the hub.
In order to reduce the height of the motor, it is therefore necessary to pay attention to, among the components of the motor, the base member that has a large impact on the total axial dimension of the motor. However, if the base member is merely made thin, the rigidity of the base member will be reduced to a great extent. As a result, if a shock is applied from the outside to the base member, it is likely that the base member will be broken and that the disk arranged within the housing will be damaged.
Accordingly, a demand has existed for a structure capable of increasing the rigidity of the base member while reducing the overall height of the motor.